I was calculating orbital elements once per second with Perl and noticed a glitch that occasionally doubled one of the derivatives for a single second.

I was using the core function "time" and noticed that the unixtime stamp would skip a second just before the event would occur.

Then I tried to see more with Time::HiRes and saw that a second would be skipped when the decimal turned over.

I ran these two lines of code concurrently in bash shells, and saw the strange results: 


perl -le 'while () { print time; sleep 1 }'

1579941920
1579941921
1579941922
1579941924 <- WTF?

perl -MTime::HiRes=time -le 'while () { print time; sleep 1 }'

1579941920.99577
1579941921.99751
1579941922.99824
1579941924.00213 <- WTF!
A third terminal running at the same time printed the missing second, but, it skipped one when it eventually turned over. 
1579941920.51386
1579941921.51823
1579941922.52046
1579941923.52163 <- OK
1579941924.52477
The interval does not seem significant: 
1579941920.99577
1.00174
1579941921.99751
1.00073
1579941922.99824
1.00389
1579941924.00213 <- WTF!
I tried a lot of things like disabling NTP and using usleep but it always skips and causes my program to flip out for a second. What is this sorcery? Thanx

In reply to missing second of time by Anonymous Monk

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